<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
</head>

<body>

    <p>单击按钮将HTML标题设置从1到6的样式显示</p>
    <button onclick="myFunction()">点我</button>
    <div id="demo"></div>
    <script>
        function myFunction() {
            var x = "", i;
            for (i = 1; i <= 6; i++) {
                x = x + "<h" + i + ">Heading " + i + "</h" + i + ">";
            }
            document.getElementById("demo").innerHTML = x;
        }
    </script>

</body>

</html>